“Energy efficiency” – it sounds so environmentally friendly and fiscally responsible, but what exactly does it mean? Is it just a fancy buzzword, or does it have a quantifiable impact on the quality and performance of our windows?
If energy efficiency is quantifiable, what makes a window energy efficient? Who does the quantifying, and how do they communicate that to the public?
What are the benefits of purchasing an energy-efficient window vs. a non-energy efficient window?
These are some of the questions that come up while shopping for new windows. Let’s break them down and provide the answers you need to make the best decision for you and your home.
Quite simply, energy efficiency describes a product’s ability to provide the same service using less energy than a similar, non-efficient product.
What does this mean to you? Energy-efficient windows are better at maintaining the temperature inside your home regardless of whether you are in the middle of an arctic freeze or a record heatwave. This helps you to avoid higher utility bills since you won’t need to run your heater or air conditioner as often as if you had a non-efficient window.
A third group – the Efficient Windows Collaborative (EWC) – is an excellent third-party resource for educational materials and minimum NFRC rating recommendations based on what area of the country you live in.
Most of us have heard of Energy Star, even if we are not sure what exactly an Energy Star rating means. The Energy Star program is a joint venture between the Environmental Protection Agency (EPA) and the United States Department of Energy.
Appliances, insulation, windows, lighting, electronics, and heating/cooling products are all tested, and their efficiencies compared to a baseline value. Products that meet a certain threshold are given the Energy Star sticker of approval.
The NFRC is an independent nonprofit organization created by industry leaders. Its purpose is to provide consumers with an objective analysis of the energy performance of a particular window, door, or skylight.
Both the Energy Star program and the NFRC quantify the energy efficiency performance of products and communicate that data to the rest of us in a standardized way that we can understand.
How do they do that? Let’s find out.
Energy Star keeps its rating pretty simplified. A product either earns the little blue star sticker of approval, or it does not. For a product to be Energy Star approved, it must meet standards for U-factor and solar heat gain coefficient. Each Energy Star sticker also indicates which of the 4 U.S. climate zones the product is rated for.
The NFRC bases its rating on the two factors considered by Energy Star as well as an additional three metrics. This means that a window that is approved by the NFRC will also meet Energy Star standards, but not all Energy Star windows will also be NFRC agreed.
The five factors that the NFRC tests and rates are:
When windows meet or exceed the rating standards, manufacturers label them with a certification sticker.
Look for the blue Energy Star sticker and the white NFRC label on the window pane.
The NFRC label is useful for comparing one window to another because it gives the numerical values the window received in each of the rating categories.
In general, energy-efficient windows tend to cost a bit more initially than less energy-efficient windows.
The trade-off is that over the lifetime of the window, energy-efficient windows will help decrease the number of your energy bills. In contrast, non-efficient windows will lead to higher heating and cooling costs.
According to Energy Star, replacing old doors, windows, and skylights with energy-efficient options can save you up to 15% annually on your energy bill.